1. Field of the Invention
The present invention concerns a method to generate an MR image based on an MR measurement (data acquisition) with a magnetic resonance system, and a correspondingly designed magnetic resonance system.
2. Description of the Prior Art
For fast generation of MR images weighted with regard to contrast, according to the prior art a contrast that is as optimal as possible is first provided by means of defined preparation modules such as IR (“Inversion Recovery”), SR (“Saturation Recovery”), T2prep (T2 preparation sequence). The signal is subsequently read out within an expanded acquisition window with the use of an SSFP (“Steady State Free Precession”) sequence, while the contrast decays to a contrast that prevails given the free precession in the rest state. Contrast changes during the MR data acquisition in k-space disadvantageously lead to artifacts in the resulting MR images. The contrast is determined by the contrast that is present at the point in time at which the middle of k-space is scanned (i.e. pre-determined data points (locations) in k-space are filled with respective measured data values).
Methods for MR data acquisition that scan (enter data into) the middle of k-space multiple times, such as radial methods, segmented spiral-shaped methods or a method known as PROPELLER (“Periodically Rotated Overlapping ParallEL Lines with Enhanced Reconstruction”), lead to an excellent signal-to-noise ratio and have other advantages, for example an insensitivity to movement of the examination subject or an accelerated parallel (operating with multiple reception coils) data acquisition. However, in the case of fast generation of MR images weighted with respect to a contrast, these methods disadvantageously have an undefined contrast that results as a mean value over the acquisition window.